Process for producing hydrogenenriched hydrocarbonaceous products from coal



United States Patent Ofiice 3,184,40l Patented May 18, 19.65

3,184,401 PROCESS FOR PRODUCING DROGEN- ENRICHED HYDROCARBGNACEOUSPROFE- UCTS FROM COAL Everett Gorin, Pittsburgh, Pa, assignor toConsolidation Coal Company, Pittsburgh, Pa., a corporation ofPennsylvania No Drawing. Filed Jan. 19, 1962, Ser. No. 167,431 3 Claims.(Cl. 208--8) This invention relates to an improved process for producinghydrogen-enriched hydrocarbonaceous products from coal. Moreparticularly, this invention relates to a process for removing ash,i.e., metallic contaminants and the like, from ash-containing coalextract prior to catalytic hydrogenation thereof.

As described in my copending applications Serial No. 61,518, filedOctober 10, 1960, now US. Patent No. 3,018,242; and Serial No. 154,451,filed November 24, 1961, now US. Patent No. 3,143,489, valuable liquidproducts such as gasoline may be derived from coal by initiallysubjecting the coal to solvent extraction, whereby a mixture of coalextract and undissolved coal residue is'bbtained. After separating theextract from the residue, the extract is catalytically hydrogenated toyield a hydrogen-enriched hydrocarbonaceous liquid suitable forsubsequent refining to gasoline, for example via a refining scheme suchas described in my copending application Serial No. 154,451, supra.

The extract obtained by the solvent extraction of coal, after beingseparated from the undissolved coal residue, contains a minute, buteconomically prohibitive, amount of metallic contaminants, sometimeshereinafter referred to as ash. If this ash is not removed from the coalextract, the ash tends to deposit on the catalyst contained in thehydrogenation zone thereby causing a more rapid decrease in the activityof the catalyst than would otherwise be experienced. Such decrease inactivity forces resort to more frequent replenishment of the catalystwith either regenerated or fresh catalyst.

While a few methods have been previously suggested for removing ash fromcoal extract (for example see US. Patent 2,141,615), these methods areeconomically prohibitive because they all involve deashing the coalextract at a relatively low temperature, generally below 100 C. Sincethe solvent extraction and catalytic hydrogenation zones are usuallyoperated at a temperature of at least 250 C., and normally 350 to 450C., the extract must thus be cooled from the relatively high extractiontemperature to the relatively low deashing temperature; deashed; andthen reheated to the hydrogenation tem perature. Obviously it isdesirable that the extract be deashed with the minimum amount of, andpreferably without any, cooling and reheating. Furthermore, deashing atlow temperatures, i.e., below 100 C., requires the addition ofhydrocarbonaceous solvent to the extract in excess of the amount usedfor solvent extraction in order to render the extract sufficiently fluidfor the deashing treatment. The deashing cost is thus increased by theincreased Volume of liquid that must be treated and by the costassociated with recovering and recycling the additionalhydrocarbonaceous solvent. Unfortunately, a method for deashingash-containing coal extract without the above disadvantages hasheretofore not been developed.

Accordingly, it is an object of this invention to provide a novel and aneconomic process for producing hydrogenenriched hydrocarbonaceousproducts from coal via solvent extraction, deashing, and catalytichydrogenation, which process is free from the aforementioneddisadvantages.

It is another object of this invention to provide a novel process fordeashing coal extract.

It is still another object of this invention to provide a novel and aneconomic process for deashing coal extract without having to excessivelycool the extract prior to deashing, and reheat the deashed extract priorto hydrogenation.

In accordance with my invention, ash-containing extract obtained via thesolvent extraction of coal is deashed in admixture with ahydrogen-transferring hydrocarbonaceous liquid at a temperature which isat least as high as the temperature at which hydrogen is transferredfrom the liquid. Normally hydrogen is not transferred from ahydrogen-transferring hydrocarbonaceous liquid below 250 C. Thetemperature at which hydrogen is transferred from thehydrogen-transferring hydrocarbonaceous liquid is hereinafter referredto as hydrogentransferring temperature. The resulting deashed extract issubsequently catalytically hydrogenated to yield the desiredhydrogen-enriched hydrocarbonaceous product.

When ash-contm'ning extract is deashed without first substantiallycooling the extract, for example, at a tem erature above 250 C.,degradation of the extract occurs such that the resulting deashedextract is more difiicult to catalytically hydrogenate and gives poorerhydrogenation yields than extract which has not been deashed. Thedegradation is manifested by the formation of coke and by the increasein the high molecular weight, hydrogen deficient portion of the extract.The benzene insoluble content of the extract is a measure of thisundesirable, high molecular weight extract portion. For example, whenextract is deashed with acidic reagents at above 250 C., not only iscoke formed, but the benzene insoluble content of the extract increasesfrom about 38 weight percent in the feed extract to more than weightpercent in the deashed extract. Surprisingly, however, when the samedeashing treatment is conducted at even higher temperatures (above 300C.), but in the presence of a hydrogen-transferring hydrocarbonaceousliquid, degradation of the extract is not only prevented, but sufficienthydrogen transfer occurs to actually reduce the benzene insolublecontent of the treated extract.

Thus, by deashing ash-containing coal extract by the process of thisinvention the following occur:

(a) The economically undesirable cooling-reheating cycle is at leastmarkedly minimized;

(b) The necessity for hydrocarbonaceous solvent in excess of the solventused for solvent extraction is eliminated, as more fully explainedhereinafter;

(c) The extract does not undergo harmful degradation during deashing;

(d) The resulting deashed extract is easier to hydrogenate and givesbetter hydrogenation yields than extract which has not been deashed; and

(e) Most importantly, hydrogenation catalyst life is markedly extendedwhen deashed extract is used.

Hydrogen-transferring hydrocarbonuceous liquids Suitablehydrogen-transferring hydrocarbonaceous liquids are those predominantlypolycyclic hydrocarbons which are partially or completely hydrogenated.Polycyclic hydrocarbon mixtures are generally employed, and arepreferably derived from intermediate or final steps of the process ofthis invention. Normally the polycyclic hydrocarbons or mixtures thereofboil above 200 C. and preferably between 260 and 425 C.

Partially hydrogenated polycyclic hydrocarbons are the most active andpreferred type of hydrogen-transfer liquids. Examples of such materialsare the di, tetra, and octa hydro derivatives of anthracene andphenanthrene; etrahydronaphthalene; and alkyl substituted spondingpartially hydrogenated compounds. If desired,

non-hydrogen-transferring liquids such as naphthalene, anthracene,biphenyl, and their alkyl substituted derivatives may be present inadmixture with the hydrogentransferring materials, for example, such isthe case when the hydrogen-transferring hydrocarbonaceous liquid isobtained from intermediate or final steps of the process of thisinvention. a

' While other materials may be admixed with the hydrogen-transferringhydrocarbonaceous liquid during deashing according to the process ofthis invention, it is important that sufiicient hydrogen-transferringliquid be present to prevent extract degradation. Normally, the rationof hydrogen-transferring hydrocarbonaceous liquid to extract which isused during deashing varies between about 0.5/1 and /1, and preferablybetween l/l and 2/1.

Specific deashing methods Any deashing process which is suitable forremoving at least a portion of the ash contained in coal extract at atemperature above 250 C.'is applicable to the process of this invention.The essence of my invention is that the deashing must be accomplished inthe presence of the hydrogen-transferring hydrocarbonaceous liquid whenextract is deashed above 250 C.

Suitable specific deashing methods are, for example, washing theash-containing extract with organic or inorganic acids such as describedin US. Patent 2,141,615. Aqueous solutions of strong inorganic acidssuch as hydrochloric acid and phosphoric acid are particularly suitable.i i

For a better and more complete understanding of my invention, itsobjects and advantages, reference should be had to the followingdescription.

Preferred embodiment I The following is a description of the. preferredembodiment of this invention. Briefly, the process of the preferredembodiment comprises:

Coal, preferably high volatile bituminous coal such. as Pittsburgh Seamcoal, is subjected to solvent extraction under the following conditions.

Solvent extraction conditions Conditions Broad Preferred Temperature 800to 500.C 375 to 420" 0. Pressure 1 to 6500 p.s.i.g-;" 1 to 600 p.s.i.g.Solvent to coal (wt. r 0.5/1 to 4/1- 1/1 to 2/1. Residence time 1 to 120min 5 to 30 min.

Any solvent extraction process may be used in the process of thisinvention. Preferably, the extraction process is as described in mycopending applications, supra.

Any of the well-known coal extraction solvents'may be used in theextraction zone. It is preferred, however, that the solvent be ahydrogen-transferring hydrocarbonaceous liquid such as previouslydescribed. Thus, the solvent can be introduced with the extract into adeashing zone without having to add additional hydrogen-transferringliquid. 7

The mixture of extract, solvent, and residue is conducted, withoutsubstantial cooling, to a conventional type separation zone wherein theresidue is separated from the extract and solvent. Preferably,substantially all of the residue is recovered from the liquidextractsolvent mixture.' The separately recovered residue may besubsequently used as boiler fuel or subjected to a fluidized lowtemperature carbonization process such as described in my copendingapplications, supra.

Any conventional type separation 'zone may be used, forexample,'filtration zone, settling zone, and the like.

The separated extract, with or without the extraction solvent, isconducted with minimal or no cooling into a deashing zone wherein atleast a portion of the ash contained in the extract is removedtherefrom.The extract is deashed in the presence of a hydrogen-transferringhydrocarbonaceous liquid.

In no event is the extract cooled below 250 C: As to whether the extractis deashed at substantially the same temperature as extraction orslightly cooled before deashing depends on the. specific deashingtreatment used. For example, when-extract is deashedwith a relativelydilute aqueous reagent, it is necessary to cool the extract below thecritical point of water, i.e., 'below- 373 C., more fully described, andspecifically claimed in the copending application of George P. Curran,Serial No. 437,626, filed February 19, 1965, and assigned to theassignee of the present application. However, if the extract is deashedwith concentrated aqueous or nonaqueous reagents, the deashing maybeconducted at substantially the same temperature as the extractiontemperature.

As previously mentioned, the extraction solvent itself may supply aportion or all of the hydrogen-transferring liquid. If desired, however,a portion or all of the solvent may be removed from the extract prior todeashing, for example, via distillation, and theextract deashed inadmixture with fresh hydrogen-transferring hydrocarbonaceous liquid.Many methods of removing solvent and adding hydrocarbonaceous liquidwill occur to those skilled in the art. The important step, however, isthat the extract be deashed in the presence of a hydrogentransferringhydrocarbonaceous liquid.

, If desired, the extract may be deashed .without first separating theresidue therefrom. Preferably, however, all of the residue and a-portionof the extraction solvent is separated from the extract (for recycle tothe extraction zone) prior to deashing.

The deashed extract is introduced into a conventional type catalytichydrogenation zone to yield hydrogenenriched hydrocarbonaceous liquidssuitable for subsequent refining to gasoline and the like. Preferably, aportion of the hyrogen-transferring hydrocarbonaceous liquid is removedfrom the deashed extract prior to hydrogenation and conveyed directllyto the refining operations.

Because at least a portion and preferably all of the .ash has beenremoved from the extract, the hydrogenation catalyst life is markedlyimproved.

As previously mentioned, a portion of the hydrogenenriched hydrogenationproducts are recycled to extraction and deashing to provide theextraction solvent and hydrogen-transferring hydrocarbonaceous liquid,respectively.

The conditions generally employed during the catalytic hydrogenation ofextract are a temperature in the range of 400 to 550 C.; a pressure inthe range of 1000 to 10,000 p.s.i.g.; a hydrogen feed rate of from 5 to100 standard cubic feet per pound, of extract; and a liquid feed rate offrom 10 to 100 pounds per cubic foot of reaction volume. The catalytichydrogenation zone may ,be any one of the conventional hydrogenationzones employed by-those skilled in the art such as a liquid phase or avapor phase hydrogenation zone employing catalyst in the form of afixed, gravitating, or fluidized bed therein. In addition, the catalystmay also be dispersed within the extract in the form of a slurry andthenintroduced into a slurry phase, catalytichydrogenation zone suchthat the catalyst is introduced into, maintained therein,

and withdrawn therefrom in the form of a slurry or a suspensoid.Suitable catalysts are, for example, metals of groups 5 to 8 of thePeriodic Chart, preferably oxides r sulfides and combinations thereof. Apreferred catalyst is one containing a metal oxide or sulfide of group 6of the Periodic Chart, i.e., molybdenum combined with a relatively minoramount of a transition group metal oxide or sulfide such as cobalt ornickel. The active hydrocracking metals are preferably supported on ahydrous oxide support such as alumina gel.

The following is an example of the use of the process described in thepreferred embodiment of this invention. Pittsburgh Seam coal is treatedin a solvent extraction zone with a solvent recovered from a previoushydrogenation of extract under the following conditions:

Process conditions:

Temperature C 380 Pressure p.s.i.g 70 Solvent/coal ratio 1.0 Residencetime hours 1.0

The solvent comprises a mixture of a 260 to 325 C. fraction and a 325 to425 C. fraction in the ratio (by weight) of 1 to 1, respectively. Theyields of the extraction treatment are:

Wt. percent original MAP 1 coal Extracts 57.8 Gases+H O 7.3 Residue 34.9

1 MAE means moisture-free and ash-free.

The extract is separated from the residue by filtration and the extractis then introduced into a topping still while the residue is carbonizedin a fluidized low temperature carbonization retort.

The solvent boiling below 325 C. is removed in the topping still. Theremaining solvent and extract are introduced into a deashing zonewherein the extract is contacted with aqueous hydrochloric acid (13.5percent acid concentration in the aqueous phase) to remove ashtherefrom. The extraction solvent that is not removed by toppingsupplies the desired hydrogen-transferring hydrocarbonaceous liquid.

The deashing conditions are as follows:

Process conditions:

Temperature C 315 Pressure p.s.i.g 1,600 Parts of aqueous phase per partextract 1.0

Process conditions:

Temperature 441 C.

Pressure 3,500 p.s.i.g.

Residence time (on fresh feed) 2.8 hours.

Catalyst COO-M003 on A1 0 base.

Wt. percent Yields: fresh feed 4 C -325 C. distillate 80.6

Because of deashing the extract prior to hydrogenation, 620 pounds ofextract per pound of catalyst may be hydrogenated before the catalystloses 10 percent of its activity as measured by hydrogen uptake.However, if the extract is not deashed and is hydrogenated under thesame conditions, only pounds of extract per pound of catalyst can behydrogenated before the catalyst is deactivated to the same extent.

Thus not only is the extract deashed without harming the extract via theprocess of this invention, but the deashing is accomplished withoutsubstantial cooling and reheating as was heretofore required.

According to the provisions of the patent statutes, I have explained theprinciples, preferred construction, and mode of operation of myinvention and have illustrated and described what I now consider torepresent its best embodiment. However, I desire to have it understoodthat, within the scope of the appended claims, the invention may bepracticed otherwise than as specifically illustrated and described.

I claim:

1. In a process for producing hydrogen-enriched hydrocarbonaceousproducts from coal wherein said coal is subjected to solvent extractionat a temperature between 300 and 500 C. to yield an ash-containingextract, at least a portion of which is subsequently catalyticallyhydrogenated to yield a hydrogen-enriched hydrocarbonaceous product, theimprovement which comprises subjecting said extract, prior to anycatalytic hydrogenation thereof, to treatment with an aqueous deashingreagent in admixture with a hydrogen-transferring hydrocarbonaceousliquid at a temperature above 250 C. but not above the temperature atwhich said coal was subjected to solvent extraction.

2. In a process for producing hydrogen-enriched hydrocarbonaceousproducts from coal wherein said coal is subjected to solvent extractionat a temperature between 300 and 500 C. to yield an ash-containingextract, at least a portion of which is subsequently catalyticallyhydrogenated to yield a hydrogen-enriched hydrocarbonaceous product, theimprovement which comprises subjecting said extract, prior to anycatalytic hydrogenation thereof, to treatment with a dilute aqueousdeashing reagent in admixture with a hydrogen-transferringhydrocarbonaceous liquid at a temperature between 250 C. and 373 C.

3. In a process for producing hydrogen-enriched hydrocarbonaceousproducts form coal wherein said coal is subjected to solvent extractionat a temperature between 300 and 500 C. to yield an ash-containingextract, at least a portion of which is subsequently catalyticallyhydrogenated to yield a hydrogen-enriched hydrocarbonaceous product, theimprovement which comprises subjecting said extract, prior to anycatalytic hydrogenation thereof, to treatment with dilute aqueous hydrochloric acid in admixture with a hydrogen-transferring hydrocarbonaceousliquid at a temperature between 250 C. and 373 C.

References Cited by the Examiner UNITED STATES PATENTS 2,606,141 8/52Meyer 208-214 3,018,241 1/62 Gorin 208--8 3,018,242 1/ 62 Gorin 20883,044,956 7/62 Burk et a1 208-252 ALPHONSO D. SULLIVAN, PrimaryExaminer.

1. IN A PROCESS FOR PRODUCING HYDROGEN-ENRICHED HYDROCARBONACEOUSPRODUCTS FROM COAL WHEREIN SAID COAL IS SUBJECTED TO SOLVENT EXTRACTIONAT A TEMPERATURE BETWEEN 300 AND 500*C. TO YIELD AN ASH-CONTAININGEXTRACT, AT LEAST A PORTION OF WHICH IS SUBSEQUENTLY CATALYTICALLYHYDROGENATED TO YIELD A HYDROGEN-ENRICHED HYDROCARBONACEOUS PRODUCT, THEIMPROVEMENT WHICH COMPRISES SUBJECTING SAID EXTRACT, PRIOR TO ANYCATALYTIC HYDROGENATION THEREOF, TO TREATMENT WITH AN AQUEOUS DEASHINGREAGENT IN ADMIXTURE WITH A HYDROGEN-TRANSFERRING HYDROCARBONACEOUSLIQUID AT A TEMPERATURE ABOVE 250* C. BUT NOT ABOVE THE TEMPERATURE ATWHICH SAID COAL WAS SUBJECTED TO SOLVENT EXTRACTION.